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Coupler
Couplers, AlsoKnownAs Couplings are mechanical assemblies that join railcars so to makeup a trains consist. This is a major part on a locomotive, wagon, or multi unit, third in importance after power-source and gauge. The Coupler assembly, AlsoKnownAs draftgear, typically includes various components: drawbar, yoke, cushioning,... There are 3 very general categories of couplers: * FullManual Couplers require a man stepping in between cars to manually couple+decouple mechanical + pneumatic + electric connections. * SemiAuto Couplers automaticly couple+decouple the mechanical connection, but still require manual pneumatic + electric connections. * FullAuto Couplers automaticly couple+decouple all mechanical + pneumatic + electric connections. Link&Pin Couplers This coupler is a FullManual design, originating on early railroads of NorthAmerica. Operation is simple but dangerous; a drawbar\buffer projecting away from the frame allows access to a vertical pin that holds a link in place. The link extends out the end of the drawbar\buffer. As railcars come together, the opposite pin is raised by hand, the link guided into the opposite drawbar\buffer, then the 2nd pin is lowered, thus joining the cars. Uncoupling is accomplished by performing the same procedure in reverse. Link&Pin Couplers have caused many injuries and deaths, and the loose links &\or pins were often stolen, rendering the coupler useless. This design was outlawed by the US Congress beginning in 1893 and the Janney\AAR coupler became standard in NorthAmerica. Link&Pin Couplers have been generally outlawed worldwide and now are only found on historic\museum rollingstock and isolated narrowgauge lines in colonial regions or on industrial\plant stock. 3Link Couplers This coupler is a FullManual design, originating on early railroads of Britain, and yet have only recently been removed from service with the retirement of legacy BritishRailways\BR goods\freight stock. The 3Link Coupler is simple yet dangerous, but was used due to its low cost. Stock fitted with this coupler have a gedged drawhook connecting to internal draftgear, along with a pair of sprung buffers on each end of the car. A 3Link chain hangs from a gedged notch in each hook shank; after 2 cars are pushed together, one of the two 3Link chains is lifted into the opposing hook. A shunting pole can be used to manipulate the chains, which is somewhat safer than being between the buffers. A disadvantage of this design is the resulting "loose" coupling, meaning several inches of slack is inherent, which must be taken up in tension as the consist accelerates; as the consist decelerates, each couplings slack again must be compressed. This causes much wear and tear on each cars structure, draftgear, buffers and lading, thus as improved coupler designs became available, only slow goods\freight stock were allowed to use 3Link Couplers. An advantage is less of the consists weight is on the locomotive as it accelerate; the reason why this coupler survived so long. The standard BR 3Link Coupler is compatible with standard BR Instanter Couplers and standard BR\EU\UIC Screw Couplers. Instanter Couplers This coupler is a FullManual design. AlsoKnownAs Close Couplers, this coupler is a mechanical improvement over 3Link Couplers; the 3Link standard center link is now replaced with a special triangular link, allowing 2 positions: LooseCoupled or CloseCoupled. LooseCoupling is used during shunting; CloseCoupling is used running in trains; a shunting pole can be used to connect\disconnect\adjust the Instanter chain. Screw Couplers This coupler is a FullManual design, and has become standard on British, Irish, and European rollingstock, both in Goods\Freight and Passenger service. Screw Couplers are a mechanical improvement over 3Link and Instanter Couplers; in essence this is a 3Link with a threaded turnbuckle replacing the chains center link. However this designs operation more dangerous, as a shunting pole can not be used; a man must go between cars and buffers to connect\disconnect this coupler. Standard BR\EU\UIC Screw Couplers are compatible with legacy BR 3Link+Instanter couplers. Janney Couplers The Janney\AAR\ARA\MCB coupler is a SemiAuto design, meaning mechanical coupling+decoupling is automatic, but PneumaticPipe+ElectricCircuit connections are seperate & manual. Inspired by Human Hands & Fingers then patented 1873~1914 by E.Janney Of USVI, the design was tested & improved again & again through many decades by the McConway&Torley Designers+Foundry, PennsylvaniaRailRoad\PRR, MasterCarBuilders\MCB, AmericanRailwayAssociation\ARA, & finally AmericanAssociatedRailways\AAR, to become a practical coupler, proven in abusive duty + extreme environments, & requiring little maintenance. Janney\AAR couplers operate much like Willison\CAK3 couplers, but with jointed\hinged nuckles instead of interlocking heads. At least one nuckle must be open to allow mating; as 2 cars come together, the nuckles are pushed closed by the palm of the opposing coupler until latch pins hold the nuckles locked. To decouple, cars are pushed together for slack, one pin is raised with a side lever allowing that nuckle to open & the cars are free to part. An advantage over Willison couplers is Janney couplers intentionally have nuckles of lower strength than the body or shank, thus acting as ShearPins if overstressed; a broken nuckle is readily replaced onsite by the train crew; a disadvantage is Willison couplers mate without concern for nuckle closed\open position. As enacted by Congress, in 1893 Janney\AARC\MCB5 couplers became standard in NorthAmerica, replacing dangerous Link&Pin couplers on Freight & unreliable MillerHookPlatform couplers on Passenger stock, greatly reducing injuries & allowing efficient interchange of rollingstock between railroads. Elsewhere Janneys are slowly accepted, having to overcome legacy coupler standards & regional politics. Janneys known as Alliance + Sharons + DropHeads + SwingHeads + Henricots are used on a small number of Freight+Passenger Unit Stock in Britain & Europe. DropHeads + SwingHeads pivot to reveal a BR\EU standard Screw coupler Hook. After 100+years of various colonial couplers, Janneys have slowly become common on Freight+Passenger Wagons in Australia+China+India+Indonesia+Japan+Korea+Malaysia+NewZeaLand+Saudi+SouthAfrica+Vietnam... Janney\AARE couplers, superceding AARD\ARAD + AARC\MCB5, became the AARE standard in 1932 for general Freight Wagons: BoxCars+CenterBeams+Hoppers+Flats+Gondolas+InterModals+AutoRacks+Reefers... The AARE is compatible with other AAR\ARA\MCB types, & is most common of all Janney\AAR types. Janney\AARF\InterLock couplers, conceived in 1901 by E.Ramsay@PrattCoalCo of USAL, became the AARF standard in 1954 for RotaryGondola+ChemicalTank Freight Wagons & later for general service Lokomotives. The AARF is compatible with other AAR\ARA\MCB types, prevents decoupling\telescoping\punctures during derailments, minimizes slack, & allows for RotaryDumping of Gondola Freight Wagons. Janney\AARH\TightLock couplers, originated with 1905 designs by E.Henricot that were manufactured at his Belgium foundry for NMBS Passenger Stock as improvements on MCB5+ARAD+Alliance designs of that era. A further improved & notably changed design, first used 1928 in America on the NewYorkCentralRailRoad, became the AARH standard in 1947 for Passenger Wagons+MultipleUnits. The AARH is compatible with other AAR\ARA\MCB types, prevents decoupling\telescoping during derailments, minimizes slack, & allows for PneumaticPipe+ElectricCircuit appliances that convert AARH\TightLocks from SemiAuto to FullAuto operation. Willison Couplers This coupler is a SemiAuto design from 1913 by J.Willison@NationalCastingsCo\NaCo of USOH for abusive environments, the rugid SemiAuto Willison coupler (in Full, 3/4, and 1/2 sizes) is a worldwide standard for narrowgauge industrial, mine, and farm railways. Enlarged and improved by NaCo+Russia in the 1930s, the Willison\CA3 was made standard for the entire RZD broadgauge railway; this version has cast letters CA3 meaning CоветскихAвто3 in Russian or SA3 meaning SovietAuto3 in English; its used across the Russian subcontinent (Russia, FinLand, Mongolia, Ukraine, Turkey, Iran...). The newer CоветскихAвтоKuppling5\CAKv version is used in Russ~Euro interchange, being compatible with both Russian\RZD CA3 and BR\EU\UIC Screw Couplers. Willison couplers operate much like Janney couplers, though with interlocking heads instead of hinged nuckles. An advantage compared to Janney couplers, Willison couplers mate without concern for nuckle closed\open position; a disadvantage, Willison couplers do not have breakaway\replaceable nuckles and head\shank failures are not repairable by the train crew. Scharfenberg Couplers This coupler is a FullyAuto design, developed in 1930s Germany, the Scharfenberg is the most common FullAuto coupler worldwide to be used on unit passenger trains (DMUs, EMUs, LRVs, Trams,...). As these couplers come together, brakepipes mate and cocks automaticly open, and a rotating cover reveals mating electric contacts. To uncouple, a release is activated remotely from the cab. Variants of the Scharfenberg, Shibata and Shinkansen couplers are standard on Japanese and Korean passenger stock. The higher cost, relative complexity, need for covers\heaters in dirty\winter service, and limited draft ratings, has prevented this coupler from being commonly used for freight. References * RailCarCouplers At OBTS Wiki * RailCarCouplers At WikiPedia * Book: The Railway Data File. Published 2000 by Silverdale Books Category:Locomotive Parts Category:Steam Locomotive Principles Category:Diesel Locomotive Principles Category:Electric Train Principles Category:Encyclopedic articles